Field
Embodiments disclosed herein generally relate to the manufacture of polishing articles used in chemical mechanical polishing (CMP) processes. More specifically, embodiments disclosed herein are related to composite polishing pads.
Description of the Related Art
Chemical-mechanical polishing (CMP) is commonly used for planarize substrates during fabrication of semiconductor devices. During CMP, a substrate being processed is mounted on a carrier head with the device surface placed against a rotating polishing pad. The carrier head provides a controllable load on the substrate to push the device surface against the polishing pad. A polishing liquid, such as slurry with abrasive particles, is typically supplied to the surface of the polishing pad. Polishing pads are consumables for typically become worn after polishing certain amount of substrates and need to be replaced.
Polishing pads are typically made by molding, casting or sintering polyurethane materials. In the case of molding, the polishing pads can be made one at a time, e.g., by injection molding. In the case of casting, the liquid precursor is cast and cured into a cake, which is subsequently sliced into individual pad pieces. These pad pieces can then be machined to a final thickness. Grooves can be machined into the polishing surface, or be formed as part of the injection molding process. These methods of manufacturing polishing pads are expensive and time consuming. Polishing pads manufactured by these methods often yield non-uniform polishing results. For example, during CMP, different areas on the substrate may be polished at different rates resulting in too much material removed (“overpolishing”) in some areas or too little material removed (“underpolishing”) in other areas.
Therefore, there is a need for a polishing pad that provides an improved polishing uniformity, and also methods for making the improved polishing pad.